This invention relates to a hot metal pipe immersion cooling apparatus to be used in a metal pipe manufacturing process for rapid cooling of pipes heated to a high temperature.
As compared with spray cooling, immersion cooling can provide a sufficient cooling effect by the use of smaller amounts of cooling water than for spray cooling and also requires less space for cooling equipment. In spite of these advantages, immersion cooling is not popular for the reasons discussed below, while spray cooling is predominantly practiced for pipe cooling purposes. That is, in cooling an immersed pipe, uniform cooling and pipe configuration must be ensured by sufficient agitation of cooling water around the pipe in order to achieve the necessary high cooling capability and uniformity of cooling. This process can be carried out so as to nearly attain its purpose by stirring the cooling water sufficiently by means of cooling nozzles directed at the outside of the pipe and arrayed in the circumferential and longitudinal directions of the pipe in a cooling tank. Nevertheless, however forceful and uniform such outside cooling may be, the influx of cooling water into the pipe at both ends thereof will become irregular since gas enclosed in the pipe and the water pressure are in such a relationship that the escape of gas from the pipe and the entry of cooling water into the pipe are intermittent. Hence, the inside of the pipe is subjected to irregular cooling in the longitudinal and circumferential directions thereof, which may result in over-all cooling unevenness and deformation of the pipe.
In the immersion cooling method, the pipe is rolled on or dropped along guides such as skids for being fed into the cooling tank. If then the pipe is in a posture with the axis thereof inclined, one end portion of the pipe is immersed into the cooling liquid ahead of the other portion and cooled earlier, so that the pipe undergoes uneven cooling along the length thereof. In addition, since the pipe to be cooled is at a high temperature, such rolling or dropping may easily cause abrasions or bruises on the pipe. Such uneven cooling of the pipe or flaws produced therein markedly impair the quality of the pipe. No conventional immersion cooling apparatus has been devised which is effective to prevent uneven cooling and flaws.